• Journal of Ecology and Environment
• /
• v.34 no.4
• /
• pp.347-355
• /
• 2011

Effects of forest thinning on community level properties have not been understood yet in Korea. We investigated regeneration patterns and trajectories after a disturbance by applying a chronosequence approach. Light availability, litter and woody debris cover, and species composition were determined for twenty 50 m line-transect samples representing a disturbance duration gradient (within 11 years). Environmental factors such as light availability and coverage of woody debris and litter changed abruptly after thinning and then returned to the pre-disturbance state. Although species richness was gained at shrub and ground layer in a limited way in both forests, cover of various functional types revealed diversity in their responses. Notably, Alnus firma stands exhibited a larger increment of cover in woody plants. Ordination analysis revealed different regeneration trajectories between natural and planted stands. Based on ordination analysis, rehabilitated stands showed movement to alternative states compared with natural ones, reflecting lower resilience to perturbation (i.e., lower stability). Our results suggest that community resilience to artificial thinning depends on properties of the dominant species. But to get more explanatory ecological information, longer-term static observations are required.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.10
• /
• pp.1427-1435
• /
• 2001

Air movement in wokplaces, whether resulting from a forced ventilation system or naturally occurring airflow, has a significant impact on occupational health. In a huge shipbuilding factory building, typical harmful factors such as fume or vaporized gas from welding and cutting of steel plates, and dusts from grinding give unpleasant feeling. From field data survey, the yearly dominant, wind directions for the shipbuilding factory building tested were northwest, northeast and southeast Among the three wind directions, the ventilation improvement was the worst for the northeastern wind. This study was focused on location of the opening vents in order to utilize the natural ventilation effectively. Instantaneous velocity fields inside the 1/1000 scale-down factory building model were measured using a 2-frame PIV system. The factory building model was embedded in an atmospheric boundary layer simulated in a wind tunnel. The modified vents improve the internal Ventilation flow with increasing the flow speed more than two times, compared with that of present vents.

• The Journal of Engineering Geology
• /
• v.4 no.2
• /
• pp.207-218
• /
• 1994

The natural constants of moving coil type geophone can be determined by free impedance and step force method. The former method was desirable for the measurement of natural frequency($f_o$), inertial mass(m) and damping factor($h_o$), but the latter method for sensitivity(G). In particular, the value by the latter method should be corrected for the noise by the long period movement of measurement device. The results of frequency characteristics from these constants operate the accelerometer and displacement system in the boundary of natural frequency.

• The Journal of Korean Academy of Prosthodontics
• /
• v.38 no.6
• /
• pp.765-781
• /
• 2000

The purpose of this study was to compare the screw loosening characteristics of three avail-able cementation type abutments: one-piece cementation type abutment; two-piece cementation type abutment using titanium abutment screw; two-piece cementation type abutment using gold abutment screw. Two implant supported three-unit superstructures were fabricated using a pair of 3 kinds of abutments for each experimental model. Cyclic loading was applied on the specimen, and made to stop when the superstructure showed movement over threshold range. The loaded cycle was counted until the machine stopped. Frequency analysis was done to measure the change of natural frequency before and after the application of cyclic load and to find the effect of screw loosening on the change of natural frequency. The specimen assembly was modeled to perform the finite element analysis to see the distribution of the stress induced by the application of preload over the screw joint and to compare the pattern of the distribution of stress induced by the external force with the change of the preload condition. The following results were obtained: 1. The failure loading cycle of two-piece cementation type abutment using gold screw was significantly greater than those of the other groups. 2. One-piece cementation type abutment applied to multi-unit restoration case did not show greater resistance to screw loosening compared to two-piece cementation type abutments. 3. Frequency analysis showed decrease in natural frequency when screw loosening occured.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.42 no.4 s.304
• /
• pp.127-132
• /
• 2005

The curve of motion indicated to waveform of the fast movement of human extracted using virtual reality or the quantity of time fluctuation of the electromagnetic signal as the quantity of electric fluctuation of the atmosphere is complex. It is important to decide exactly the signal property as the inflection point for the observation signal. When the signal is mixed by noise signal, the traditional method is difficult to detect the inflection point. In this paper the noisy signal is eliminated by wavelet thresholding method and the filter using natural observation theorem is applied. It shows that the inflection point of the signal waveform can be detected exactly.

• Journal of Engineering Education Research
• /
• v.22 no.5
• /
• pp.49-55
• /
• 2019

Folded structure is widely applied in various engineering fields. Many of the Japanese folding fans in the Edo era (1603-1868) have been successfully blended with the processing technology of "natural materials" that is the origin of Japan's "Monodzukuri" (craftsmanship) and its application "artistic originality". The charm of a fan lies in the diversity of stereoscopic expression not born in plane representation. For example, the effects of folds, the expression of the front and back sides flowing from the front to the back by double-sided description, and the two-layer effect of raising the backside from the surface using the permeability of Japanese paper, the calculated depiction are also seen. Moreover, by handling the fan, it also produced an illusion effect which skillfully calculated the change due to movement of the viewpoint. Students experience the natural materials such as Japanese paper, bamboo and starch paste, which are the materials of paint and fan at the time, and processing method, and know the difference with the current one. This study is to verify the effectiveness of engineering education which gains experience by making concrete fans and to understand deeply this traditional technology with the artistry of a Japanese fan at the same time. And we can learn from the characteristics of the fan to Japan's history and culture.

• Journal of Korean Medical classics
• /
• v.26 no.3
• /
• pp.11-18
• /
• 2013

Objective : This paper was designed to confirm the relation between Li Dong-yuan(李東垣)'s theory of internal injury(內傷學說) and Neo-confucianism(新儒學)'s academic orientation, particularly Zhang Heung-qu(張橫渠)'s 'Qi-monism(氣一元論)'. Method : Through a comparative literature review, I searched for the commonality between Li Dong-yuan(李東垣)'s theory of internal injury(內傷學說) and Neo-confucianism(新儒學)'s academic orientation, particularly Zhang Heung-qu(張橫渠)'s 'Qi-monism(氣一元論)', and also examined the difference in the meaning of 'Primordial Qi(元氣)' in Qi-monism and that Lee Dong-yuan proposed. Result & Conclusion : The central theme of Neo-confucianism, 'Staying on the Golden Path(允執厥中)', has a commonality with Li Dong-yuan's theory of internal injury that emphasized Primordial Qi, and the concepts of "Great Vacuity as Qi(太虛卽氣)", "Two Properties Inherent in a Single Object(一物兩體)", and "the Nature of Acquired Disposition(氣質之性)" have commonality with the concepts of "The Given from the Vacuity of Natural World(所受於天)", Up & Down Movement(升降運動), and Yin Fire(陰火) of Primordial Qi in Li Dong-yuan's theory of internal injury respectively. However, the concept of Primordial Qi in the Theory of Qi-monism refers to the building blocks of all things in the universe, whereas the concept of Primordial Qi that Li Dong-yuan proposed has no meaning of component of body but driving force that maintains the phenomenon of life.

• Journal of the Korean Geosynthetics Society
• /
• v.16 no.4
• /
• pp.177-190
• /
• 2017

This paper presents the results of an experimental study on the effect of large underground station construction method under an existing pile supported bridge using reduced-scale model tests. A series of tests were conducted on design alternatives using 1g models for different design options for which tunnel structures were created considering the similitude law. Deformation fields obtained using the PIV analysis and LVDTs together with strains in tunnel structures were used to investigate the effect of the construction methods on the pile supported bridge. The results of the tests demonstrated that the pipe roof structure is more efficient in limiting the ground deformation as well as the settlement of bridge foundation than a 2-Arch tunnel. It is also shown that the PIV analysis can be effectively used in analyzing ground tunneling induced ground movement for cases in which a construction sequence governs ground movement.

• Journal of Korean Medical classics
• /
• v.13 no.1
• /
• pp.102-116
• /
• 2000

In Cheon Won Gi Dae Ron(天元紀大論), Cheon(大) means Nature, Won(元) means sources, Gi(紀) is Gang Gi(綱紀) that means rules or regulations, so Cheon Won Gi(天元紀) means sources and rules of change that make Nature phenomenons. This volume treats of cause that weather change of Nature caused by, and its general rules, and presents fundamental notions and systems of measuring of 'Five elements' evolutions and Six kinds of natural factors(五運六氣)'. So named Cheon Won Gi Dae Ron(天元紀大論). This article of the research on the Cheon Won Gi Dae Ron(天元紀大論) can be divided into 3 chapters. Chapter 1 presents a theory that the principle of changes of creations' birth, groth and extinction is complished by sympathizing with Hyeong(形) of Ji(地) and Gi(氣) of Cheon(大) by rules of movement of O Un Yum Yang(五運陰陽). Chapter 2 presents theories that Tae Heo(太虛) makes Won Gi(元氣), and this Won Gi(元氣) makes the change of creations' birth, groth and extinction, and movement of O Un(五運) controls creation of nature. And treats of that 'excessive and short(太過不及)' that is made by a quality of Gi(氣) and ups and dons of Hyeong(形) controls weather of year. In Chapter 3, Cheon O Ji Yuk(天五地六) regard six and five as Yong(用). And A Cycle that movment that sympathizing with O Un(五運) and Yuk Gi(六氣) is Il Gi(一氣) as 30 years, and Il Ju(一周) as 60 years. And presents that O Un(五運) and Yuk Gi(六氣) that Gan Ji(干支) control.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.12
• /
• pp.3035-3041
• /
• 2014

The steadicam effects is widely used in production of the 3D animation for natural camera movement. Conventional method for steadicam effects is using keyframe animation technique, which is annoying and time consuming process. Furthermore it is difficult and unnatural to simulate camera movement in real world. In this paper we propose a novel method for representing steadicam effects on virtual camera of 3D animation. We modeled a camera of real world into Maya production tools, considering gravity, mass and elasticity. The model is implemented with Python language, which is directly applied to Maya platform as a filter module. The proposed method reduces production time and improves production environment. It also makes more natural and realistic footage to maximize visual effects.